C PROGRAMMING LECTURE C-language Computer Fundamentals

History of C  C  Evolved by Ritchie from two previous programming languages, BCPL and B  Used to develop UNIX  Used to write modern operating systems  Hardware independent (portable)  By late 1970's C had evolved to "traditional C"

History of C  Standardization  Many slight variations of C existed, and were incompatible  Committee formed to create a "unambiguous, machine-independent" definition  Standard created in 1989, updated in 1999

Language Types  Three types of programming languages 1. Machine languages Strings of numbers giving machine specific instructions Example: Assembly languages English-like abbreviations representing elementary computer operations (translated via assemblers) Example: MOV AL, NUM1 ADD AL, NUM2 MOV VAL, AL

Language Types, Cont. 3. High-level languages Codes similar to everyday English Use mathematical notations (translated via compilers) Example: grossPay = basePay + overTimePay

High-level Languages  “high-level” is a relative term  C is a relatively low-level high-level language  Pascal, Fortran, COBOL are typical high-level languages  Java, Python, Perl, VB are examples of high-level high-level languages  Application specific languages (Matlab, Javascript, VBScript) are even higher-level.

C Language C-language  C is a high-level language.  Writing a C code. {turbo C, DevC++}  For DevC++  Compiling a C code. {F9}  Compile & Execute. {F11}

Character Set of C-Langauge  Alphabetic Letters  A-Z  A-z  Numbers  0-9  Special Characters  +,-,*,/,%  {,},[,],”,, =,(,) etc C-language

Word  Reserved Words  Also called keyword  Reserved for language and language has special meanings for these reserved word  autoifbreak int case long  Registercontinue returndefault short do  sizeofdouble static else structswitch  extern typedef float union dsignedfor  unsigned goto whileenum void const  Volatile char C-language

Words C-language  User Defined Words User / Programmer defines(creates, declares) to solve his own problem Could variable, function, structure, class name  int radius; radius is a reserved word  char name[50]; Name is a reserved word

Variable Naming Rules  Can’t be reserved word  Must start with alphabetic letter or underscore only  Must not contain any special character even space character is not allowed  Not two variables can have same name within same scope  C/C++ is case sensitive  etc C-language

Codding Rules  Every statement must end with semicolon  Every program must have a main() function  We place two statements on the same line; but they must be separated with semicolon  Program must include respective header file if some required to be used in the program  Variable naming rules  etc C-language

Error  Syntax Errors  Due to violation of grammatical rules on language  int first number;// invalid  Logical Errors  Due wrong use of logic or formula  Area=3.14+radius+radius;// * must be there instead of +  Run Time Errors  Occur when specific condition meets  Divide by zero C-language

My first C program! C-language #include using namespace std; // program prints hello world main() { cout<<"Hello world!"; } Output: Hello world!

Example 1 C-language #include using namespace std; // program prints a number of type int main() { int number = 4; cout<<“Number is”<< number; } Output: Number is 4

Example 2 C-language #include // program reads and prints the same thing int main() { int number ; cout<<“enter number: ”; cin>>number; cout<<“\nNumber is ”<< number; return 0; } Output : Enter a number: 4 Number is 4

more and more C-language #include using namespace std; int main() { /* this program adds two numbers */ int a = 4; //first number int b = 5; //second number int answer = 0; //result answer = a + b; }

Operators C-language OperatorsSymbols Increment Operators++ -- (Postfix), (Prefix) Asthmatic Operators* / % + - Shift Operator > Relational Operators Bitwise Binary Operators & | ~ ^ Logical Operators&& || !

Some more Arithmetic Operators C-language  Prefix Increment : ++a  example: int a=5; b=++a; // value of b=6; a=6;  Postfix Increment: a++  example int a=5; b=a++; //value of b=5; a=6;

Some more Data Types C-language

Contd… C-language  Modulus (remainder): %  example: 12%5 = 2;  Assignment by addition: +=  example: int a=4; a+=1; //(means a=a+1) value of a becomes 5 Can use -, /, *, % also

Contd… C-language  Comparision Operators:, =, !=, ==, !, &&, ||.  example: int a=4, b=5; a<b returns a true(non zero number) value.  Bitwise Operators: >, ~, &, |,^.  example int a=8; a= a>>1; // value of a becomes 4

Operator Precedence C-language  Meaning of a + b * c ?  is a+(b*c) basically All operators have precedence over each other  *, / have more precedence over +, -.  If both *, / are used, associativity comes into picture. (more on this later)  example : 5+4*3 = 5+12= 17.